1. Field of the Invention
The present invention relates to an image generating apparatus, and more particularly, it relates to an image generating apparatus comprising a side plate on a side surface of a chassis.
2. Description of the Background Art
The structure of a bearing member for a rotary shaft mounted on a side surface of a chassis of a printer is known in general, as disclosed in Japanese Utility Model Registration No. 3060471 or 3060949, for example.
Each of the aforementioned Japanese Utility Model Registration Nos. 3060471 and 3060949 describes the structure of a bearing member, having a bearing supporting a rotary shaft, a stop section for fixing the bearing member to a side surface of a chassis and a projecting portion for positioning the bearing member, mountable on the side surface of the chassis by inserting the bearing and the stop section into a hole provided on the side surface of the chassis and rotating the bearing member thereby engaging the stop section of the bearing with the side surface of the chassis while engaging the projecting portion for positioning the bearing member with a recess portion provided on the side surface of the chassis.
In the bearing member described in each of the aforementioned Japanese Utility Model Registration Nos. 3060471 and 3060949, however, a side plate provided independently of the bearing member must be mounted in order to cover the side surface of the chassis. Therefore, the side plate must be mounted on the side surface of the chassis independently of the bearing member, and hence the number of components is disadvantageously increased.
In this regard, there is generally proposed a thermal transfer printer having a side plate, integrally provided with a bearing supporting a rotary shaft, mounted on a side surface of a chassis as an exemplary image generating apparatus. The structure of this conventional thermal transfer printer is described with reference to FIGS. 15 to 18.
The conventional thermal transfer printer comprises a metal chassis 101, a resin side plate 102, a platen roller 103, a paper feed roller 104, a platen roller bearing member 105 and a paper feed roller bearing member 106, as shown in FIGS. 15 and 16. The chassis 101 has first and second side surfaces 101a and 101b opposed to each other. The first side surface 101a of the chassis 101 is provided with an ink sheet cartridge receiving hole 101c for receiving an ink sheet cartridge (not shown), a long hole 101d and a positioning hole 101e, as shown in FIGS. 16 and 17. The ink sheet cartridge receiving hole 101c is provided with a notch 101f receiving a paper feed roller bearing 102b of the side plate 102 described later. As shown in FIG. 17, the first side surface 101a of the chassis 101 is provided with stepwise first and second notches 101g and 111g, stepwise first and second notches 101h and 111h and a rectangular notch 101i. A stop portion 121g is provided in the vicinity of the stepwise first and second notches 101g and 111g, while another stop portion 121h is provided in the vicinity of the stepwise first and second notches 101h and 111h. The second side surface 101b of the chassis 101 is provided with the platen roller bearing member 105 for supporting the platen roller 103 and the paper feed roller bearing member 106 for supporting the paper feed roller 104.
As shown in FIGS. 16 and 18, a platen roller bearing 102a supporting the platen roller 103, the paper feed roller bearing 102b supporting the paper feed roller 104, a boss 102c for positioning the side plate 102 with respect to the first side surface 101a of the chassis 101 and hooked stop sections 102d, 102e and 102f for mounting the side plate 102 on the first side surface 101a of the chassis 101 are integrally provided on the side, mounted on the chassis 101, of the resin side plate 102, to protrude from the side plate 102. The stop sections 102d and 102e are so provided on the side plate 102 that hooks 112d and 112e vertically extend upward respectively. The stop section 102f is so provided on the side plate 102 that a hook 112f horizontally extends. The boss 102c for positioning the side plate 102 with respect to the first side surface 101a of the chassis 101 is provided on a position separated from the platen roller bearing 102a by a distance A, as shown in FIG. 18. The side plate 102 is further provided with a notch 102g for receiving the ink sheet cartridge (not shown) when the side plate 102 is mounted on the first side surface 101a of the chassis 101.
A method of mounting the side plate 102 on the first side surface 101a of the chassis 101 is now described with reference to FIGS. 16, 19 and 20.
First, the side plate 102 is parallelly brought into contact with the first side surface 101a of the chassis 101 in a state deviating from the first side surface 101a of the chassis 101 by a distance B, as shown in FIG. 19. At this time, the platen roller bearing 102a of the side plate 102 is inserted into the long hole 101d provided on the first side surface 101a of the chassis 101. Further, the paper feed roller bearing 102b of the side plate 102 is inserted into the notch 101f provided on the first side surface 101a of the chassis 101. In addition, the stop sections 102d and 102e of the side plate 102 are inserted into the first notches 101g and 101h of the chassis 101 respectively, while the stop section 102f is inserted into the notch 101i. In this state, the boss 102c of the side plate 102 is not yet inserted into the positioning hole 101e provided on the first side surface 101a of the chassis 101.
Then, the side plate 102 is slid along arrow C (horizontal direction) shown in FIG. 19. Thus, the platen roller bearing 102a and the paper feed roller bearing 102b of the side plate 102 also move with the side plate 102. The positioning boss 102c of the side plate 102 is engaged with the positioning hole 101e provided on the first side surface 101a of the chassis 101. Following this sliding of the side plate 102 along arrow C, the stop sections 102d and 102e are moved from the first notches 101g and 101h to the second notches 111g and 111h respectively, to engage with the stop portions 121g and 121h respectively. The stop section 102f is also moved from the notch 101i to the stop portion 111i provided on the notch 101i to engage with the same, following the sliding of the side plate 102 along arrow C. Thus, the side plate 102 is mounted on the first side surface 101a of the chassis 101, while the positioning boss 102c of the side plate 102 engages with the positioning hole 101e provided on the first side surface 101a of the chassis 101, thereby positioning the side plate 102 with respect to the first side surface 101a of the chassis 101. In this state, the platen roller bearing 102a of the side plate 102 is not in contact with but separated from an end of the long hole 101d provided on the first side surface 101a of the chassis 101 in the sliding direction with a clearance D, as shown in FIG. 20. Further, the paper feed roller bearing 102b is not in contact with but separated from an end of the notch 101f provided on the first side surface 101a of the chassis 101 in the sliding direction with a clearance E.
In the conventional thermal transfer printer shown in FIGS. 15 to 20, however, the positioning boss 102c of the side plate 102 positions the side plate 102 in the sliding direction by engaging with the positioning hole 101e provided on the first side surface 101a of the chassis 101, to disadvantageously result in the clearance D between the platen roller bearing 102a and the end of the long hole 101d in the sliding direction. Therefore, it is difficult to improve positioning accuracy of the platen roller bearing 102a with respect to the first side surface 101a of the chassis 101 since the platen roller bearing 102a cannot be positioned by coming into contact with the end of the long hole 101d in the sliding direction.